In operation of a gas turbine, turbine blades and vanes are exposed to hot temperatures and, in case of the blades, to high loads due to the rotation of the turbine rotor to which the blades are fixed. In order to cope with such extreme conditions turbine vanes and blades are usually made from so-called superalloys with high temperature resistance and high creep strength. Known superalloys which are used in turbine blade and vane manufacturing are, for example, disclosed in EP 1 204 776 B1, EP 1 319 729 A1, WO 99/67435 A1 or WO 00/44949 A1. The alloys mentioned in these documents are based on nickel (Ni) or cobalt (Co) and show considerable heat resistance and creep strength. When high creep resistance has been needed in the state of the art alloys with low chromium content i.e. up to about 10% by weight chromium content, like the alloys known under CM247DS (with a high density) and IN100 (with a low density), have been used frequently. With less emphasis on creep resistance, alloys with high chromium content, i.e. above at least about 11% chromium content, like the alloys known under IN792 (with moderate density) or Rene77 (with low density) have been utilised. Recently, a promising high creep resistance alloy being called SCB444 and having high chromium content was developed. This alloy, which is described in U.S. 2003/0047252 A1, has the following composition by weight:    Co (cobalt): 4.75 to 5.25%    Cr (chromium): 11.5 to 12.5%    Mo (molybdenum): 0.8 to 1.2%    W (tungsten): 3.75 to 4.25%    Al (aluminium): 3.75 to 4.25%    Ti (titanium): 4 to 4.8%    Ta (tantalum): 1.75 to 2.25%    C (carbon): 0.006 to 0.04%    B (boron): ≦0.01%    Zr (zirconium): ≦0.01%    Hf (hafnium): ≦1%    Nb (niobium): ≦1%    nickel (Ni) and any impurities: complement to 100%.